The present invention relates to an oxygen absorbent packet for packing an oxygen absorbent, and, more particularly, to an oxygen absorbent packet suitable for storage together with drugs in a sealed container.
When drugs such as some antibiotics, vitamins, live bacteria drugs, enzyme drugs and crude drugs are stored, the drugs may be oxidized or discolored and their effects are often degraded. In order to prevent oxidation of the drugs, according to conventional techniques, an antioxidant agent is added to drugs, drugs are encapsulated, or drug pills are covered with a coating. Since the conventional antioxidation techniques are not completely satisfactory, an oxygen absorbent is used in some cases. However, the following problem is presented by the method using an oxygen absorbent.
In general, most granular or solid drugs have a small water content and tend to degrade due to humidity. For this reason, these drugs must be kept in a dry state, and a desiccant is often used.
When a drug kept dry by means of a desiccant is stored with an oxygen absorbent, the water-containing oxygen absorbent must be held together with the drug and the desiccant is a single sealed container. In this state, moisture contained in the oxygen absorbent is absorbed by the drug or the desiccant to decrease the oxygen absorption rate. In the worst case, the oxygen absorption reaction is interrupted. In general, drugs must withstand a high-temperature (40.degree. C. or more) test under pharmaceutical regulations. When an oxygen absorbent is used under such a severe condition, the moisture is absorbed from the oxygen absorbent by the drug or desiccant, and thus degradation of the drug is inevitable.
A conventional oxygen absorbent is packed with an air-permeable packing material. On the other hand, most of the drugs must be protected from humidity. Evaporation of water from the oxygen absorbent must therefore be minimized. At the same time, the oxygen absorption effect must be maintained. The air permeability of a packing material is preferably 60,000 to 80,000 sec/100 ml air in compliance with JIS P8117. The air permeability of a packing material having a large surface area is difficult to maintain within this range. Most commercially available granular and pill type drugs are contained in small bottles or cans. When the oxygen absorbent is packed in a small package, productivity efficiency is degraded and the other appearance of the packet is poor. Moreover, an oxygen absorbent is too large to be sealed in a sealed container.